NEW BRUNSWICK — Cool water will do the trick of eliminating bacteria just as much as hot water when you wash your hands.

That's a conclusion of a new study by Rutgers University which looked at 21 people over a six-month period who washed their hands several times in water at a temperature of 60, 79 and 100 degrees after a high levels of a harmless bacteria was put on their hands.

The findings could have an impact on health codes regulating restaurants.

“People need to feel comfortable when they are washing their hands but as far as effectiveness, this study shows us that the temperature of the water used didn’t matter,” said Donald Schaffner, a distinguished professor and extension specialist in food science at the university.

The results could have an impact on the new guidelines the Food & Drug Administration issues about hand washing in restaurants and in food industries. Current guidelines, according to Schaffner, require a water temperature of 100 degrees for hand washing.

“This study may have significant implications towards water energy, since using cold water saves more energy than warm or hot water,” Schaffner said

The recommended time spent washing hands could also be affected. “Also, we learned even washing for 10 seconds significantly removed bacteria from the hands.”

The CDC currently recommends washing hands for 20 seconds or long enough to hum "Happy Birthday" twice from beginning to end.

Contact reporter Dan Alexander at

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